I think that whole "#1 publisher" nonsense should be disallowed on this board. It's a crutch, and it's meaningless.
I played all of those games, and, sorry but Flight Sim, Halo Infinite and Forza Horizon 5 are just not great games. And Psychonauts 2 was extremely average, and also was not a home grown MS game anyway. Both Sony and Nintendo put out WAY better games last year, because .... I actually played them. You know, instead of looking at some silly "award" that no one ever cared about beforehand.
By the way, to address the thread in general. It's because MS doesn't understand gaming. They understand numbers and spreadsheets and trying to get people to sign up for software subscriptions. Phil Spencer and co. obviously don't have a clue about the craftsmanship of games that can reach level where some people consider them "art." Both Sony and Nintendo have people throughout the executive leadership that love games. They understand them. How many times has Spencer said they have the "best Xbox lineup in history" only for it to be a total dud? It's because he literally has no comprehension about what's good or bad. Why else would he be proud of the releases they have so far, when they are actually a complete embarrassment?
Easy answer to the question.
Just want to interject here!
I'm a PS guy as you all know but Xbox definitely did have games last year, as the record shows..... it's up to Xbox fans to decide if they liked those games, as that is down to individual taste.
But I agree in theory with @DynamiteCop that last year was way better than this year, even if to you and me as PS users, that doesn't mean much.
(The Xbox guys are outnumbered here, so lets be understanding to some point)